Flotation method for potash ores



United States Patent ()fiice 3,341,135 Patented Sept. 12, 1967 3,341,135FLOTATION METHOD FOR POTASH ORES Martin Wilson, Anaheim, Calif, assignorto United States Borax & Chemical Corporation, Los Angeles, Calif., acorporation of Nevada No Drawing. Filed Sept. 16, 1964, Ser. No. 397,03610 Claims. (Cl. 24120) This invention relates to methods for obtainingdesired mineral values from ore by froth flotation using a novelflotation reagent combination, and especially for obtaining potash frompotash ore.

In the reccovery of desired mineral values, such as potash, from ores,the ores can be comminuted to a small size and submitted to frothflotation procedures to separate the mineral from the other constituentsof the ore. The long chain aliphatic amines are well known as collectorreagents in such froth flotation procedures. However, it has been foundthat potash of larger than 14 mesh particle size cannot be eflicientlyfloated with higher alkylamines alone. Accordingly, it has been purposedthat certain auxiliary reagents can be employed in combination with theamines in order to promote flotation of the large size particles. Forexample, my US. Patent 3,059,774 issued Oct. 23, 1962, discloses andclaims the use of certain alkylnaphthalenes, the chloro and hydrogenatedderivatives thereof, alkylmercaptans and dialkylsulfides, and their arylderivatives, dialkyl sulfides and dialky polysulfides as auxiliaryreagents. Also, my copending US. patent application Ser. No. 169,963,filed Jan. 30, 1962, now Patent No. 3,149,788, discloses and claims theuse of indane and alkylindans as auxiliary reagents. These combinationsprovide an excellent grade (purity) of product, but the recovery is notas high as desired.

The present invention provides a novel flotation reagent combinationwhich gives an excellent grade of product and also a very high recoveryof product. The superior reagent combination of this invention comprisesan admixture of a long chain aliphatic amine collector reagent and apolycyclic aromatic auxiliary reagent having at least three rings in themolecule. The oreis treated in the usual manner associated with frothflotation techniques, well known to those skilled in the art.

Thus, there is provided by the prevent invention the method of obtainingdesired mineral values from ores by froth flotation which comprisescomminuting said ore, pulping the comminuted ore, treating the resultantore pulp with a flotation reagent comprising an admixture of a longchain aliphatic amine collector reagent and a polycyclic aromaticauxiliary reagent having at least three rings in the molecule,subjecting said treated or pulp to a froth flotation cell, andrecovering said mineral values from said flotation cell.

The polycyclic aromatic auxiliary reagents useful in this invention haveat least three rings in the molecule. They are high-boilinghydrocarbons, consisting mostly of the I higher alkyl derivatives ofcondensed ring systems, which are obtainable as residues from thecracking of mineral oils. Many are known as reformate ends, cycle oilsor products from cycle oils. They are generally characterized by adistillation range within about 500 to about 800 F., low pour points,such as below about 20 C., and relatively low viscosities, such as SSUof less than about 100 at 100 F. Usually such polycyclic aromatic oilsoccur as mixtures of condensed ring systems having 3 to about 5 ringsand are predominantly tricyclic and tetracyclic hydrocarbon compounds,such as the acenaphthenes, fluorenes, phenanthrenes, pyrenes andbenzonaphthenes. Such mixtures can also contain minor amounts of otherlower ring systems such as alkylindans, Tetralins, and naphthalenes.

The amine collector reagents employed in the present invention are thoseused by ore refiners in conventional flotation processes. The collectorreagents are long chain aliphatic amines, saturated and unsaturated,having from about 7 to about 18 or more carbon atmos and are mostcommonly prepared from beef tallow. They are usually used as the saltsof the amines, the most commonly used salt being the acetate, and theycan be purchased commercially as mixed aliphatic amine acetates. Theweight ratio of amine to polycyclic aromatic reagent is preferably about1: 1, although greater or lesser amounts can be employed and aredesirable for some ores.

The ore is treated, following normal procedures, prior to beingsubjected to flotation with the regeant combinations of the presentinvention. Thus, the ore is comminuted, such as by grinding to asuitable particle size of about 8 mesh. The comminuted ore is thenpulped by slurring'it in a saturated brine composed of the solubleconstituents of the ore. If the ore contains clay contaminants, it ispreferred to deslime using conventional procedures, such as by screeningthe slurry through, for example, a -mesh screen to remove the clay andfines. The ore pulp is then treated with the flotation reagentcombination and the treated ore subjected to a conventional frothflotation cell. Preferably, the deslimed feed is split prior toflotation into coarse and fines and the two fractions treated separatelywith the flotation reagents to avoid excessive consumption of thereagent. After treatment (reagentizing), they are recombined forflotation.

In a preferred embodiment of this invention, I employ as an auxiliaryreagent, a combination of the abovedescribed polycyclic aromaticreagents and at least one additional material selected from the groupconsisting of indane, the alkylindans in which said alkyl substituentshave from one to about eight carbon atoms, alkylnaphthalenes and thehydrogenated derivatives thereof, in which said alkyl substituents havefrom one to about eight carbon atoms. By employing said combination, anexcellent recovery of very high grade ore is readily obtained. Thecombinations also retain the advantages of low pour point, lowviscosities (preferably less than about 70 SSU at 100 F.) as well asrelatively high volatility which results in oil-free ore concentratesafter any drying procedure. A further advantage of the blends is theflexibility which can be obtained by varying the proportions of thecomponents in order to adjust the auxiliary reagent to the possiblechanging characteristics of the ore (degree of liberation). However, aratio of polycyclic aromatic to alkylindan or alkylnaphthalene of about1:1 is normally employed.

The indanes, alkylindans, alkylnaphthalenese, and their derivatives aredescribed in my US. Patent 3,059,774 and my copending application Ser.No. 169,963, referred to above. They can be employed as the purecompounds, as mixtures of such compounds or as mixtures with relatedcompounds. Whenever such mixtures are employed, the indanes,alkylindans, alkylnaphthalenes, and their derivatives should be presentin such amount as would provide the equivalent of the reagent as wouldbe required in the flotation process if they were to be used in asubstantially pure state.

The following examples are presented to illustrate the present improvedprocess, but the invention is not to be considered to be limited to thespecific examples given.

Example I Sylvinite ore was ground to a -8 mesh size and was slurried ina saturated brine composed of the soluble constitutents of the ore. Theslurry was then deslimed through a 100-mesh screen to remove the finesand insoluble matter, and the deslimed ore was wet-screened and dividedinto two fractions, one fraction containing the +20 mesh particles andthe other fraction containing the -20 mesh particles. The +20 meshfraction was conditioned with 0.32 pound/ ton of a 50-50 mixture ofamine colector reagents (50% of a mixture predominantly hexadecyl andoctadecyl amines and 50% of a mixture predominantly hexadecyl, octadecyland octadecenyl amines) in the form of the acetic salts, and 0.5 pound/ton of furfural extract of FCC light cycle oil, having a boiling rangeof 600-800 F. and containing about 81% polycyclic compounds of at leastthree rings, including acenapthalenes, alkylfluorenes, phenanthrenes,pyrenes and higher homologues, 12.6% sulfur analogues, and about 2%alkylnaphthalenes and alkylindans. The -20 mesh fraction was conditionedwith 0.8 pound/ton of starch and 0.1 pound/ ton of the mixture of aminecollector reagents. The fractions were recombined and added to a Fagflotation cell along with some clear saturated brine. The slurry wasthen aerated from the bottom of the cell and as the froth formed at thesurface it was removed carrying with it substantially all of the potash.97.35% of the KCl was recovered, based on the amount of KCl in the orepulp after desliming. The material analyzed 60.25% K 0.

In another test following the same procedure except that no aromaticauxiliary reagent was used, only 72.38% of the KCl was recovered. Thematerial analyzed 61.71% K 0.

Examples II-VII The procedure of Example I was followed except thatvarious polycyclic aromatic materials were substituted for the lightcycle oil auxiliary reagent. The amounts of reagents used were the sameas Example I, including the amount of auxiliary reagent. The followingresults were obtained.

Collier Heavy PD is a product of Collier Carbon and Chemical Corporationhaving a distillation range of 390 to 450 F. and described aspredominantly aromatic polycyclic condensed rings, but containing 25%alkylnaphthalenes. The oil, which is from thermal cracking, is freepouring at 10 C.

Collier A500 is a product of Collier Carbon and Chemical Corporationdescribed as heavy end of reformate and is predominantly aromaticcondensed rings, containing about 62% tricyclic and tetracycliccompounds and 14% alkylnaphthalenes. It has a distillation range of 566to 760 F. and viscosity SSU 100 F. of 63.

Panasol AN7 is an aromatic residual fuel oil, a product of AmocoChemical Company having a distillation range of 468 to 713 F., viscositySSU at 100 F. of 70, and pour point of 30 F. It is described asconsisting of a mixture of predominantly tricyclic and tetracycliccompounds.

Provalent 4A is a product of Mobil Oil Company, described as a heavyaromatic oil having a distillation range of 417 to 734 F., viscosity SSUat 100 F. of 45, and pour point of 10 F. It contains about polycycliccompounds having at least three rings in the molecule, 7% alkylbenzenesand 34% alkylnapthalenes and alkylindans.

Examples VIII-X The procedure of Example I was followed except that the+20 mesh fraction was treated with a combination of the light cycle oiland an alkylnaphthalene or indane, as well as the amine mixture, and the20 mesh fraction was treated with 0.13 lb./ton of the amine mixture aswell as the starch. The following results were obtained.

Amount Purity, Recovery of Light Addltlonal Reagent Amount PercentProduct, Cycle 01] (lb./ton) K20 Percent (lbJton) K20 VIII 0.25 Mixedmethylnaphthalenes (B.P. 240.5-244 0)-... 0. 25 60. 49 93. 42 IX 0.125Indane" 0. 375 60. 86 92. 36 X 0. 25 Panasol AN2 0. 25 60. 32 03. 93

50 Note.Panasol AN2 is a product of Amoco Chemical H Percent Purity ofCompany, having a boiling range of 370 to 550 F. and Auxlhary Reagent gzg sg l g i containing 45% alkylnaphthalenes, 20% alkylindans andalkyltetralins and 28% polyalkylbenzenes. Viscosity 37 O Bunker HeavyCycle on 96.84 59.93 SSU at 100 r s as? as 0 ier 50 G Amoco Pauasol AN 796. as 60.17 Examples Xl-X Provalent 4A 96.32 61. 26 None 72. 38 61. 71

The procedure of Example I was followed except that the +20 meshfraction was treated with 0.2 lb./ton of the amine mixture and acombination of the light cycle oil and as an additional reagent,petroleum fractions consisting predominantly of mixtures of alkylindansand alkylnaphthalenes. The 20 mesh fraction was treated with 0.5 lb./tonof starch and 0.1 lb./ton of the amine mixture. The following resultswere obtained.

Note.-Panasol ANS is a product of Amoco Chemical Company, having aboiling range of 400 to 750 F., viscosity of 46 SSU at 100 F., andcontaining 79% alkylnaphthalenes and 6% alkylindans and alkyltetralins.

Collier A4000 is a product of Collier Carbon and Chemical Corporationdescribed as a reject stream from the hydrodealkylation ofalkylnaphthalenes. It has a boiling range of 400 to 440 F., viscosity of30 SSU at130 F., and contains 45% alkylindans and alkyltetralins, 45%alkylbenzenes and 5% naphthalene.

Although the examples illustrate the recovery of potash from potash ore,the novel flotation reagents of the present invention can also be usedin the recovery of other desired mineral values by froth flotationprocedures, such as the recovery of spodumene from silica.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims or the equivalent of suchbe employed.

I, therefore, particularly point out and distinctly claim as myinvention:

1. The method of obtaining potash from potash ore by froth flotationwhich comprises comminuting said potash ore, pulping the comminuted orewith brine, treating the resultant ore pulp with a flotation reagentcomprising an admixture of a long chain aliphatic amine collectorreagent and a polycyclic aromatic hydrocarbon auxiliary reagent havingthree to five rings in the molecule and having a distillation rangewithin about 500- 800 F., subjecting said treated ore pulp to a frothflotation cell, and recovering said potash from said flotation cell.

- 2. The method according to claim 1 in which said potash ore iscomminuted by grinding to a particle size of at least about 8 mesh.

3. The method of obtaining potash from potash ore by froth flotationwhich comprises comminuting said potash ore, pulping the comminuted orewith brine, treating the resultant ore pulp with a flotation reagentcomprising an admixture of a long chain aliphatic amine collectorreagent, a polycyclic aromatic hydrocarbon auxiliary reagent havingthree to five rings in the molecule and having a distillation rangewithin about 500-800 F., and at least one material selected from thegroup consisting of indane, alkylindans in which said alkyl substituentshave from one to about eight carbon atoms, alkylnaphthalenes and thehydrogenated derivatives thereof, in which said alkyl substituents havefrom one to about eight carbon atoms, subjecting said treated ore pulpto a froth flotation cell, and recovering said potash from said frothflotation cell.

4. The method according to claim 3 in which said potash ore iscomminuted by grinding to a particle size of at least about 8 mesh.

5. The method according to claim 3 in which said polycyclic aromatichydrocarbon auxiliary reagent is a mixture of predominantly tricyclicand tetracyclic hydrocarbon compounds.

6. In the method of recovering potash from potash ore by the frothflotation of an ore-brine pulp using a long chain aliphatic aminecollector reagent, the improvement which comprises employing as anauxiliary reagent a polycyclic aromatic hydrocarbon oil having threerings in the molecule and having a distillation range within about500-800 F.

7. The method according to claim 6 in which said aromatic hydrocarbonoil has a viscosity of less than about 100 SSU at 100 F.

8. In the method of recovering potash from potash ore by the frothflotation of an ore-brine pulp using a long chain aliphatic aminecollector reagent, the improvement which comprises employing as anauxiliary reagent an admixture of a polycyclic aromatic hydrocarbon oilhaving three to five rings in the molecule, and having a distillationrange within about 500-800 F. and at least one material selected fromthe group consisting of indane, alkylindans in which said alkylsubstituents have from one to about eight carbon atoms,alkylnaphthalenes and the hydrogenated derivatives thereof, in whichsaid alkyl substituents have from one to about eight carbon atoms.

9. The method according to claim 8 in which said polycyclic aromatichydrocarbon oil is a mixture of predominantly tricyclic and tetracyclichydrocarbon compounds.

10. The method according to claim 8 in which said admixture has aviscosity of less than about SSU at F.

References Cited UNITED STATES PATENTS 1,43 8,435 12/ 1922 Frederick209-166 1,476,530 12/ 1923 McCullough 209-166 1,577,328 3/1926 Lewis209-167 1,590,196 6/1926 Klees 209-166 3,016,143 1/1962 Trachta 209-1663,059,774 10/ 1962 Wilson 209-166 3,149,788 9/1964 Wilson 209-166FOREIGN PATENTS 1,008,222 5/ 1957 Germany.

HARRY B. THORNTON, Primary Examiner. R. HALPER, Assistant Examiner.

6. IN THE METHOD OF RECOVERING POTASH FROM POTASH ORE BY THE FROTHFLOTATION OF AN ORE-BRINE PULP USING A LONG CHAIN ALIPHATIC AMINECOLLECTOR REAGENT, THE IMPROVEMENT WHICH COMPRISES EMPLOYING AS ANAUXILIARY REAGENT A POLYCYCLIC AROMATIC HYDROCARBON OIL HAVING THREERINGS IN THE MOLECULE AND HAVING A DISTILLATION RANGE WITHIN ABOUT500*-800*F.